I always find it interesting that people outside the US think this is a complete joke when really it’s just… only slightly exaggerated.
Many gas stations have 64oz cups by default. I haven’t seen it in awhile, but the 128oz soda was real and used to be widely available.
I am a ‘big’ man and I would say that where things peaked in American culture as far as ridiculous sizes go was when a Starbucks-like chain operating in Florida was offering a 42-ounce version of a frappucino-type drink that Starbucks only provided a 24-ounce version of, this was shortly before Super Size Me came out which started to change the culture on those things.